Recently, radiation therapy practice has incorporated improvements in computers and networking, radiation therapy treatment planning software, and medical imaging modalities (such as, computed tomography (“CT”), magnetic resonance imaging (“MRI”), ultrasound (“US”), and positron emission tomography (“PET”)). In some cases, techniques are used for the planning and delivery of radiation therapy. For example, a method of treating a moving target, such as a tumor of a lung, can include “gating,” or delivering radiation only when the target is within a specified window of trajectory. This method is inefficient because the target is only being irradiated for periodic intervals of time.
Another method of treating a moving target is referred to as breathing synchronized delivery (“BSD”). This technique utilizes an anticipated track, or path of motion, for a target to follow during treatment. To do so, a plan is developed that assumes the target will remain on the anticipated track, which has an anticipated period and phase throughout the entire treatment plan. Audio and visual guidance can be used to prompt a patient to follow the rigidly defined track. However, following a strictly defined pattern may be difficult for a large portion of radiation therapy patients.